In recent years, there has been a full-fledged proliferation, in households, of home theater systems that combine a set top box (hereafter called STB) which receives a digital broadcast or a cable television (hereafter called CATV) broadcast, a television, a speaker, and a Digital Versatile Disk (DVD) player. With these devices, it is possible to implement the reproduction of mufti-channel audio, for example 5.1 channel audio, by setting the respective devices with the use of a remote control (see Non-Patent Reference 1).
There is proposed a technique (device linkage apparatus) for switching between outputting audio only from a television reception apparatus and outputting the audio from a speaker connected to an amplifier, in linkage with the ON/OFF operation of the power switch of the amplifier (see for example Patent Reference 1)
For example, the device linkage apparatus in the below-mentioned Patent Reference 1 is included in an AV amplifier that is capable of configuring a surround system by being combined with a television reception apparatus. In other words, the device linkage apparatus in the aforementioned Patent Reference 1 can perform switching between the use of the surround system and the independent use of the television reception apparatus.
FIG. 1 shows a block diagram of the AV amplifier in the below-mentioned Patent Reference 1.
With such a device linkage apparatus in an AV amplifier 40, when a power switch 41 of the AV amplifier 40 is turned ON during use of the surround system, a change-over switch 50 is switched to a center audio amplification circuit 48. As a result, an audio signal supplied to an audio input terminal 43 from a reproduction device such as a Video Tape Recorder (VTR) or a Laser Disc (LD), for example, or a television reception apparatus connected to the AV amplifier 40 is supplied to surrounding speakers, via a DSP 45 and through an audio output terminal 49. With such a device linkage apparatus in the AV amplifier 40, when the power switch 41 of the AV amplifier 40 is turned OFF during independent use of the television reception apparatus, the change-over switch 50 is switched to a television audio input terminal 51. As a result, television audio processed in the amplification circuit of the television reception apparatus is supplied to a speaker of the television reception apparatus, via the AV amplifier 40.    Non-Patent Reference 1: High Definition Multimedia Interface specification Version 1.2    Patent Reference 1: Japanese Unexamined Patent Application Publication No. 5-153520
However, with the device linkage apparatus in Patent Reference 1, there is the problem of having to take the trouble of operating the power to the AV amplifier in order to switch between the use and non-use of the surround system. In other words, a user needs to turn ON the power to the AV amplifier when causing a speaker connected to the AV amplifier 40 to output audio, and needs to turn OFF the power to the AV amplifier when causing a speaker included in the television reception apparatus to output the audio, other than the speaker connected to the AV amplifier.
Thus, the present invention is conceived in view of the aforementioned problem and has as an object to provide a device linkage apparatus which reduces the operating load of the user and causes devices to be linked appropriately.